A vehicle can be equipped with deployable safety devices designed to reduce injury to a pedestrian struck by the vehicle. For example, the vehicle may be equipped with one or more pedestrian air bags and/or a device for changing the inclination angle of the hood. Since these devices are only to be deployed in the event of a pedestrian impact, the deployment system must be capable of reliably distinguishing pedestrian impacts from impacts with other objects. However, equipping a production vehicle with the required sensors can be both costly and difficult. Accordingly, what is needed is a way of detecting pedestrian impacts that is more practical and cost-effective.